The invention relates to an optical disc drive system, and more particularly, to a detecting apparatus for detecting statuses of an optical disc and a method thereof.
When an optical disc drive system reads data from an optical disc, it first detects the status of a sector presently accessed by an optical pick-up head to determine whether the sector contains data or not. The status of a sector could be blank, not blank, or defect. Only if the sector contains data, i.e. not blank, the system will retrieve data from the optical disc. The system determines the sector as a non-blank sector when it detects a radio frequency (RF) signal with larger amplitude, determines the sector as a blank sector when it detects the RF signal with smaller amplitude, or determines the sector as a defect sector when it detects the RF signal with a low direct current (DC) level. However, a wrong decision as to the status of a sector is easily made at the transition between a blank region and a data region (i.e. the non-blank region) of the optical disc. This is due to the reflectivity variation between the blank region and the data region. The reflectivity of the blank region for a first kind of optical discs (such as CD, DVD discs) is usually higher than that of the data region. Therefore, a large DC value variation of the RF signal will be detected by the system when the optical pick-up head moves from the blank region to the data region, thereby mistaking the data region for the defect region. For a second kind of optical discs (such as low-to-high Blu-ray discs), the reflectivity of the data region may usually be higher than that of the blank region. Therefore, a large DC value variation of the RF signal will be detected by the system when the optical pick-up head moves from the data region to the blank region, thereby mistaking the blank region for the defect region. Moreover, because the RF signal is influenced in the defect region, the amplitudes of the RF signal in the defect region will sometimes be small. In this situation, the system may mistake a defect region for a blank region. It is obvious that if the above situations cannot be avoided or alleviated, the accuracy of the data read by the system and even the stability of the system will be seriously degraded.